U.S. Attorney Patrick Fitzgerald, known for prosecuting a long list of highly publicized federal cases including convictions of vice presidential aide Lewis "Scooter" Libby and Illinois Gov. Rod Blagojevich, announced Wednesday he is resigning.

Fitzgerald was appointed by former President George W. Bush and began serving in the post on September 1, 2001. He was kept on by President Barack Obama and ended up serving for nearly 12 years, making him the longest serving U.S. attorney ever in Chicago.

In his announcement Fitzgerald said he would step down officially on June 30, and leaves the Justice Department after serving nearly 24 years.

In a modest announcement, Fitzgerald praised the career attorneys in the Northern District of Illinois, where he presides.

"I tried not to get in their way," Fitzgerald said.

Fitzgerald, 51, says he has no future employment plans and, after this summer off, the father of two young children will "consider his career options."

The announcement came as a bit of surprise to Justice Department officials who had been informed of his decision this morning.

Attorney General Eric Holder issued a statement praising Fitzgerald for his commitment to serve "the American people and the citizens of Illinois with the utmost integrity and a steadfast commitment to the cause of justice."

"Over the years he has gained the trust of two presidents and the unwavering confidence of four Attorneys General, and I am deeply grateful to him for his service and his friendship over the years," Holder said.

Fitzgerald first became widely known when he participated in the prosecution of Omar Abdel Rahman for the 1993 bombing of the World Trade Center. He also helped prosecute the terrorism defendants tied to the 1998 bombings of the U.S. embassies in Kenya and Tanzania.

Fitzgerald managed to keep amicable relations with both Republican and Democratic administrations and sidestep or ignore political accusations. However he received blistering criticism from supporters of Vice President Richard Cheney for the indictment of Libby, who in 2007 was sentenced to prison for lying to investigators about what he told reporters about CIA operative Valerie Plame Wilson.

Blagojevich, the former Illinois governor, was convicted last year of corruption charges in connection with his efforts to profit from appointing the successor to the U.S. Senate seat vacated by Barack Obama when he became president. Blagojevich began serving a 14-year sentence in March.

Speculation about Fitzgerald's future in legal circles has included the possibility of his being named FBI director to succeed Robert Mueller, whose term expires in September, though lucrative offers may be forthcoming from the private sector.

Fitzgerald has scheduled a news conference for Thursday morning in Chicago.